心肌缺血中心率变异性的符号动力学分析

目的基于心率变异性（HRV）研究，分析心肌缺血发生过程中心率的动态变化特性以探讨自主神经活动的变化和影响。方法从长时ST段一T波终点（Long．term ST-T）数据库中，选取13个记录中共193个心肌缺血时段及其前后各5min的对照时段。选用符号动力学方法分析不同时段的RR间期序列，利用重复测量的方差分析对缺血前和缺血中以及缺血后结果进行检验；以线性拟合的方式，分析心肌缺血时自主神经响应模式随缺血持续时间的分布。结果较之心肌缺血前后，心肌缺血过程中0v％的显著增加和2UV％的显著减小反映了交感神经活性的增加和迷走神经活性的减弱，但这种自主神经平衡向交感神经更占优移动的趋势随着缺血持续时间的延长而减小，提示可能存在的对心脏的保护作用。结论符号动力学分析为研究心肌缺血中自主神经的调制提供了一个敏感的工具。

Symbolic dynamics of heart rate variability in myocardial ischemia

Objective To investigate the autonomic modulation and influence during myocardial ischemia based on analysis on heart rate dynamics with heart rate variability(HRV). Methods From 13 free download ECG records in long-term ST-T(LTST)database, 193 ischemia episodes were extracted for analysis, and 5 min intervals before and after each selected isehemia episode were selected as control ones. Using symbolic dynamic analysis method, the indexes during different stages were calculated. The repeated measurement analysis of variance was introduced for statistic test. And the distribution of autonomic reflex mode to isehemia duration was analyzed by linear fitting. Results Symbolic analysis detected an increase in the percentage of non-varlable patterns (0 V%) and a decrease in the percentage of very variable patterns(2 UV%), indicating a more sympathetic predominance compared with the baseline. But the trend of the shift in autonomic balance towards sympathetic predominance reduced with the extension of ischemic duration, suggesting a possible protection for heart. Conclusion Symbolic dynamic analysis is capable of identifying changes in autonomic modulation and seems appropriate for elucidating the neural pathophysiological mechanisms occurring in myocardial ischemic episodes.